Variable condenser



W. DUBILIER VARIABLE CONDENS ER March l2, 1929.

Filed June l0, 1924 DUBILIER, ONEW YORK, N. Y.,

'WILLIAM PORATION, OF NEW YORK., N. Y.,

gii'oagg Parma OFFICE Assrcrrron 'ro DUBILIEB coNDnNsEn con;-V ACORPORATION or DELAWARE.

VARIABLE c'oNnENsna.

Applicaties 'mea :une 1o,

This invention relates to improvements in electrical condensers;especially electrical condensers so designed that the capacity thereofcan be varied as desired, to suit practical conditions,

fin' obj eet ot this invention is to provide a variable electricalcondenser which is simple in structure, which can bel convenientlymounted upon a panel or other support, which lll is easyy to operate,and which is so constructed that, upon the .parts being adjusted in apredetermined manner, the condenser will afford, with the greatestsharpness and accuracy, the precise measure of capacity required'.

Other objects and advantages of this invention will appear from thefollowing description, taken with the accompanying drawings, in whichthe preferred embodiment of my invention is illustrated. But thisdisclosure is ot course explanatory only, and l may make changes in thedevice actually shown Without departing from the scope and spirit ofthis invention, to the full extent indicated by the broad and generalmeanings oi the terms in which the appended claims are expressed. K Onthe drawings, Figure 1 is a top plan ot the exterior of the casing of avariable condenser according to my invention;

Figure 2 is a longitudinal section on the line 2-"2 of Figure 1;

Figure 31s a bottom plan of such a condenser; Y

Figure 4 is aplan view of a detail, show-.1 ing the manner in which theconducting ele`V ments; of the condenser `are' disposed in the requiredrelationto eachother; and Figure 5 is a section taken on the line 5-5 ofFigure 4:. f

The same. characters on the drawings identify the same parts throughout.y

Indicated by the numeral 1 is a casing of suitable size and shape of anyconvenienty material. This casing is shown as being closed at the sides,ends and top, but open at the bottom. On the inside of the casing is apair of elements of conductive material 2, such as plates or sheets ofthin metallic foil,

and associated with these elements is a plate onmcmber 3, the plates 2being disposed between this plate and the top 4 of the casing. Theelements 2, the plate 3 and theother op. erative parts of the condenser,are situated in a chamber 5, enclosed by the casing 1; this casing asthe drawings illustratefbeing ob- 1924. serial N'o. 719,116.l

long or rectangular, andof the height or depth required; While thechamber 5 and .plate 3 therein are of corresponding shape.

, Onl the top of the easing is an exterior ciru cular protuberance 6 incentral position and 80 passing through this protubera-nce is a bore '7,which is counterbored or enlarged. at the protuberance 6 to form aconical seat 8. The bore 7 receives'the'reduced end 9 of a stem or shaft10, having thereon a peripheral Vflange o5 or collar 11 which isconical, to fit the. seat 8; and the top-4 of the casing also carries'v.centralboss 12 projecting from the inner suryface of the top down intothe chamber 5 and terminating at its lower end in. a conical seat 13;the bore 7 passing through the protubervin concentric relation. Into thethreaded opening 14 is screwed a central externally 80 threaded head ornut 15, whichhgsa threaded bore 16 therethrough of the same dia-meter asthe bore 7 vand adapted to aline therewith.

The face of the head 15, which is presented to the boss 12, is bored outconcentric with 35 the bore 16, as indicated at 17 ,and the bottom ofthe recess 17 is made conical, as indicated at 18, to lit the conicalseat 13, l'at the inner end of the boss 12. To makeconnection betweenthe stem or shaft 10, and the head 15,-

I thread the extremity ofthe lower end '9`of this stem and screw it intothe threaded bore 16 of the head 15. When the stem 10 is turned up to asufficient extent, the threads of the ex tremity of the end/9 will drawthe headfl 95 against the boss 12, and cause the conical collar 11 ofthe stem 10, and the conical surface 18v of the nut '15, to makev firmcontact with the conical seats 8 and 13; but withoutproducing anyinterference to therotation of the stem of the head 15,-when thecondenser is to be operated. The inside of the bore 7 is of coursesmooth.

For the purpose of securing the stem 10'to the head 15 in rigidrelation,I may employ a 105 binding screw 19, which'enters the threadedbore 16 from below. and vengages the extremity of the threaded .end 9.When Vthe bindingv screw 19 isturned up tightly enough against theextremity of the end 9, it is capable of causing the threads of-theend 9to engage so tightly with the threads in the bore 16, that when the stem10 is turned, the head 15 will always turn with it in either direction,and no `lost motion b etween the end 9 and the head 15 will occur. Overvthe outer end 'of thehinding screw 19, I may screw a nutl 20, and uponone face or end of this nut will rest a per- I forated washer 21. At 22is indicated a spring. in the'form of aresilient plate of curved metalof substantially the same width as the' plate 3; the upper face of thisplate being conca-ve and the 'lower face convex. -The extremities of thespring plate 22, therefore, engage the lower side of theplate 3, and

the middle of this spring will rest upon the.

washer 21. Of course, the plate 22 will be perforated to allow the screw19 to pass Vthrough it. The. middle portion of `this spring platewilllie between the washer 21 and the lower end of the head 15, and the nutw20 will be turned .up on the screw 19 just` enough to cause the washerto press against ,the spring, but not enough to make this spring plateor device 22 turn Aor revolve about the screw 19 as an axis, when theshaft 10 is rotated to turn the head 15 in the threaded opening 14 ofthe plate 3. `When the nut 20 is screwed up just enough to grip thewasher,

2l, and the plate 22 lightly, against the lower end of the head 15, thenut may be locked on the screw by any suitable means;

It will now be apparent that when the shaft 10 is turned, the end 9, thehead 15, the binding screw 19 .and the nut 20, will rotate together inunison, while the member 3 and plate 22 will not rotate, being heldagainst rotation by the opposite lateral surfaces of v'the ends of thespring 22, on account of the resiliency of the metal, rise with it.Hence, the ends of this spring always press up forcibly against thebottom of the plate 3, and thus compensate for any looseness or wearupon the threads on the outside of the head 15,

Y and the inside of the aperture 14; that is, the

' jacent ends separated, as indicated particu-v spring will always holdthe top faces of the threads in the aperture 14 firmly against the.lower `faces of the threads on the outside of the head 15.

. The elements 2 are in the same plane and in longitudinal alinement,but have their adlarly in Figures 2, 4 and 5. 1 prefer to place theseelements between covering sheets of mica 23 which are provided at thecenter with registering openings 24. These openings are of smallerdiameter than the width of the space between the adjacent ends of theeleiyyeaaae ments 2, and the opposite ends of the elements 2 are allowedIto project somewhat and are 'bent over upon the outside of one of theturned ends of the plates 2 between them. f

Vif ith this construction, the two elements can be handled asa unit, andwhen placed between the member 3 and top 4, the boss 12 will passthrough the registering apertures 24. I also employ in the space betweenthe plate 3 and top 4 of the casing, a pair of leafsprings in the formof curved metal plates similar to the spring plate 22 and indicated inFigure 2, by the numerals 26 and 27. The spring 26 engages at itsextremities against the under side of the top 4, and is perforated inthe middle to enable the boss 12 topass through it. The metal composingit isso set that the lower face of this spring is concave and pressesdown upon the upper one of the mica sheets 23. Upon the other hand, thespring 27 is convex on its upper face, resting at its ends upon the topof the plate 3 and pressing up in the middle against the lower 'micasheet; both plates or springs A26 and -27 having central apertureslikethe aperture 2 4, to permit the boss 12 to pass through them.`

The manner in which the condenser is operated to vary the capacity willnow be clear. If each of the elements 2 is connected to the twoextremities of an electrical circuit, the capacity of the condenser canbe decreased by turning the shaft 10, upon which, in practice, asuitableknob will be affixed, so as to make the plate 3 move'down and thusincrease the distance between itand thetop 4. The two springs 26 and 27will then both become more convex on the faces which they present to theplates 2, that is, the ends of these two springs will move farther awayfrom--the-elements 2. But if the shaft 10 is turned to make the head lesA15 lift the plate 3, the lower spring 26 is caused to become Hatter andthrough its midL dle portion it acts to press upward'upon the micasheets 23, lifting the mica sheets and the I elements 2 somewhat andflattening out, to some extent, the upper-spring 26. The effect of thisis th' bring the ends of the two springs 26 and 27 closer tothe elements2 and thusv bridge to a greater extent, the space between these twosheets. rlhe capacity of the condenser is thereby increased, because thesprings 26 and 27- also serve as condenser plates, although they are notdirectlyV con.- nected in circuit. IThey may be called floatingv7 orisolated plates.

The ends o f the condenser have openings therein to receive insulatingbushings 28, againstthe outer extremities of which are insulatingwashers 29. Inside of the casing, against the adjacent extremities ofthe` bush# ings 28, I place metallic washers 30, which are of suchvshape, that they have a straight edge iat/omelia orl the casing; whilethe inner ends of these socket pieces carry heads 33 to lit against thevwashers30., and these heads 33 are joined by conductors v34, one to eachof the metal clips 25. Into the bores 32 of the sockets 31, are insertedbinding screws 35 4to enable electrical conductors tobe connected to thesockets 31,

the washers 29, Inlay place locking washers 36 encircling the exteriorend of the sockets- 3l, the exterior ends of these sockets being eX-panded'against'the washers 36, so as -to bind the heads 33, the-washers30, the bushings 28, thewashers 29 and 36, and the socket pieces,`

f fragile and brittle, and any stress to which it firmly together.

The stem or shaft 10 may carry a projection 37 to engage with a 'stop 38upon the protuberance 6, to limit the shaft 10 to one revo- .lution, butobviously, I may so design the condenser to'permit' less than onerevolutlon,

or more than a complete revolution of the shaft 10.

The opposite ends of the casing l may have projections 39 with threadedopenings 40 to enable the condenser to be secured to a bench, table,wall or other support; and the top may have projections or bosses 41,with threaded apertures 42 to enable the condenser to be secured to theinside of a panel; that 'is, upon the rear face, which will be aperturedto permit the shaft 10 .to pass` through it, and have i the knob affixedto-this AIshaftlocated on'the outer face or front of the panel.

-The open lower end of 'the easing may have a shoulder- 43 to receive aclosure 44, which may be fastened in place by any well-known means. Imayalso provide the inside. of the casing with vertical ribs 45, at eachsideA of the chamber 5, to prevent any turning or twisting of the plates3, or the springs 22, 26 and 27, or of the mica sheets 23 holding theelements 2, and I may provide the washers 3() with projecting portions46 to engage a straight edge or recess of the heads 33 upon the innerends of the sockets 3l, so that when the screws 35 are tightened, thesesockets will not turn in the bushings 28. locking'pin isindicated at 47in Figure 3 to illustrate an example of the means employed to secure thenut 2O in the desired positionupon the screw 19; but obviously,nolocking `pin is needed at this point because after the screw 19has beentightened, the nut 2() can be fastened thereon as required, by drivingthe point of a punch into the threads at the point 47.

From the foregoing description, itv will be seen that't'he parts of thecondenser are all correctly assembled and maintained `in true" position,so that when the stem l() is rotated through any particular arc, thedesired capacity will always result, because whenever the Ishaft 10 isturned to a predetermined extent, the member 3 actuating the spring 27and likewise the spring 26, will always occupy the same correspondingposition, and so whilev the two springs are bridging the -space betweenthe elements 2, no looseness can take place between the head l5 and theplate 3, because of the compensating elicct of the spring 22. vTheprecise capacity desired can thus always be secured, and the ac- 'curacyof the/condenser maintained. and on the outside of the casing andagainst 1 may be subjected may produce cracks in the mica which"willexpose the elements 2 more or less, and thus destroy or greatly impairthe efficiency of the condenser.

Hence, the conductors 34 must be made light and flexible, so that whenthe condenser and the mica move up or down, the mica sheets are notcaused to bend at the ends and `thus no force whatever is applied to themica, except'the force of compression exerted at the middle by theopposed convex faces ot' the springs 26 and 27. This force, however, isof such a character that it can do no damage to the mica in any of thepositions which the mica and the metal sheets 2 may assume in the smallrange ot' movements permitted to them. Ot' course the shape of thecasing 1 need not necessarily be oblong,

`but may be varied as desired.

It is understood that in t-he foregoing disclosure, the bott-om view ot'the condenser shown in Figure 3 omits` the closure 44401' the sake ofclearness. -In Figure 2, the electrically conductive sheets 2, the micaplates 23 and the spring plates V26 and 27 are shown in edge or sideview, and not in section, for the sake ofcouvenience and clearness.

The structure of the condenser proper comprising the plates -2 and thecooperating parts 26 and 27, is not. recited in the claims of thisapplication, but is set forth in the claims of my copending application,Serial No: 719,115, filed June 10th, 1924.

Having described my invention, what I believe to be new and desire tosecure and protect. by Letters Patent ot the United States is 1. Avariable electrical condenser' including a casing, an operating member,a rotatable head inthe casing engaging said member, saidhead being heldagainst movement along the axis of 4its rotation. and said member beingheld against rotatable movement, but being free to more bodily alongsaid axis, and a compensating device engaging both said is seated, anoperating stem engaging thev head and projecting through the casing tothe outside for rotating the head, the stem havingl a collar on' theoutside or' the casing to'engage the casing so that the head may ro tatewithout shifting along the airis of the stem, an operating membei in thecasinoand liavinthr'eaded engagement with the tliead, and a bow springhaving its middle portion supported adjacent said head and itsextremities bearing upon said member in hold said member and said headinprecise engagement.

3. An electrical condenser comprising elements of electricallyconductive material in alinementwitli each other, but having theiradjacent ends separated, dielectric materia-1 between the elements, anoperating membci to cause bridging of sai'd elements and thus vary thecapacity of the condenser, a head to have rotary engagement with saidmember and enable the member to be moved bodily along the axis ofrotation, and a comv pensatingdevice to hold the head and the member inprecise engagement with each other. l

4. A condenser comprising elements of electrically conductive materialin alinement with each other, but having their adjacent ends separated,dielectric material between.

theclements, a member to cause bridging of said elementsand vary thecapacity of the condenser,I said'm'ember being free to have bodilymovement but held' against rotation, and a rotatable head havingthreadedengagement with the member, said head being held against movement alongthe axis of rotation, and a compensating bow spring having its middle.portion supported adjacent said head, and having its ends bearingagainst thc member to maintain the head and the member in preciseengagement.

5. A condenser comprising elements of electrically conductive materialhaving their ends separated, dielectric material between the elements, aplate to bridge said elements and vary the capacity of the condenser,anl operating member for said plate, a head having rotary engagementwith said member, said head being held against movement along the axisof rotation; while said member is supported to be held against rotation,while being tree for bodily rnove'ment, and a spring associated withsaid head and member to maintain them in precise engagement.

6. A condenser comprising elements of electrically conductive materialhaving their rotatable head inl said casing, Saidy middle portionsupported adjacent said head and its extremities bearing against saidmember to secure precise engagement of the head and member.

7. A condenser comprising electrically conductive elements withintervening dielectric material, a casing, a member adapted to cause thecapacity of the condenser to be varied; a rotatable head in the casinghaving thread'- ed engagementwith the member, said head being heldagainst shifting along its axis ot rotation, and said member beingallowed to have bodily movement but being held against rotation, and acompensating device engaging both said head and said member to maintbainprecise engagement ofthe head and memel, i 8. A condenser comprisingelectrically conductive elements separated by a dielectric, an

operating member, a casing in which saidA member is enclosed, arotatable head having threaded engagement with the member, a projectionagainst which saidhead is seated, the

stem for saidl head projecting through the cas .ing to the outsidethereof and having a collar to engage 'the outside of the casing andhold the head against said projection to prevent axial movement of thehead, the member being mounted to have bodily movement, but held againstrotation, and a bow spring having its middle portion supported adjacentthe head and having its extremities bearing upon 4the member to hold themember and the head in precise engagement.

9. An electrical condenser including a casing, an operatin member tocause' variation of the capacity othe condenser, a head in the casingadapted to have rotary engagement ioo with said member and enable themember to j be moved bodily along the axis of rotation, and acompensating device mechanically engaging the head and member to holdthe head. precise engagement withv and the member in each other.

i0. A condenser comprising conductive ele- 'ments separated bydielectric material, a

member adapted to 'cause variationof the capacity oi" the condenser,said member being free to have bodily movement, but held againstrotation, and a rotatable head having threaded engagement with themember, said head being held against movement along the axis ofrotation, and a compensating bow spring havingits middle portionsupported adjacent said head,l and having itsA ends bearing against themember to maintain the head and the member in precise engagement.

ll. fi condenser Comprising electrodes separated by insulation, anoperating plate, adapted to canse variation of the capacity of thecondenser, a head having rotary en gagement with said plate, said headbeing held against movement along the axis, While said plate issupported to be held against rotation, While being free for bodilymovement along said anis, and a spring engaging both said head andmember to maintain them in precise engagementD 12 A condenser comprisingconductive elements separated by a dielectric, an operating member'forcausing variation of the 0u-,

paeity of the condenser, said member being held against rotation, butmounted to be free for bodily movement,I a head having threadedengagement with said member and mounted to be rotated, but engaged to beheld against movement along the axis of rotation, and a spring engagingboth said head and said plate to secure precise engagement thereofn 1ntestimony whereof I aftix my signature.

WILLAM DUBILIER.

